Selective modification of a nonwoven surface

ABSTRACT

Improved fastening systems are described. More particularly, improved fastening systems for disposable absorbent articles are described.

BACKGROUND

The present invention relates to improved fastening systems. Moreparticularly, the present invention related to improved fasteningsystems for disposable absorbent articles.

Conventional disposable absorbent articles, such as disposable diapers,have typically included a bodyside liner, an outer cover and anabsorbent core disposed between the outer cover and the bodyside liner.The disposable absorbent articles have generally defined a front region,a rear region and a crotch region which extends between and connects thefront and rear regions. Such conventional disposable absorbent articleshave also included fastening systems which are configured to secure thearticle on the wearer's waist. The disposable absorbent articles havealso been constructed with various types of elasticized portions at thewaist and leg opening regions. Such elasticized portions have been usedto reduce the leakage of body exudates from the disposable absorbentarticle and improve the appearance and fit of the article about thewearer.

Typically, the fastening systems on conventional disposable absorbentarticles have included a pair of fasteners located on the outermostcorners of the article in one of the waist regions. Such fasteners havebeen configured to releasably engage a complimentary fastener in theopposite waist region of the disposable absorbent article. For examplethe fastening systems have included a pair of mechanical fasteners, suchas hook material, located on the outermost corners of the disposableabsorbent article in the rear region of the article. Such systems havealso included a complimentary fastener, such as a loop material panel,located on the outer surface of the outer cover of the disposableabsorbent article in the front region of the article. In such aconfiguration, the disposable absorbent article has been positionedbetween the legs of the wearer and the hook material has been releasablyattached to the loop material panel to secure the article about thewaist of the wearer. In some disposable absorbent articles, the loopmaterial panel has been removed, and the hook material has beenreleasably attached to the outer cover of the diaper, know as a fastenanywhere configuration.

However, conventional disposable absorbent articles which are configuredas described above have exhibited several shortcomings. For example,with the desire for disposable absorbent articles to be more clothlike,manufacturers have made the outer cover and the loop materialincreasingly more fluffy, soft and correspondingly susceptible toabrasion. As a result, these clothlike materials become abraded upondisengagement of the mechanical fasteners. This abrasion may cause adecrease in aesthetic appeal, as well as a decrease in functionality ofthe attachment system.

As a result, there has remained a need for improved fastening systems.Moreover, there has remained a need for improved fastening systems fordisposable absorbent articles.

SUMMARY

The present inventors undertook intensive research and developmentefforts concerning improving fastening systems. While conducting theirresearch, the present inventors discovered unique methods of modifyingfastening systems that resulted in improved fastening systems and thuswell suited for use is disposable absorbent articles. One version of thepresent invention involves a fastening system suitable for incorporationinto a disposable absorbent article, the fastening system having a malecomponent having a plurality of hook elements and a female componentadapted for releasable engagement with the male component. The femalecomponent comprises a web having a fibrous structure. The femalecomponent contains at least a first area and a second area, the firstarea being modified such that a peak shear force to disengage the malecomponent from the first area is at least 10% less than a peak shearforce to disengage the male component from the second area. Further, atleast a portion of the female component is stretchable.

Another version of the present invention relates to an absorbent articlehaving a fastening system. The fastening system having a male componenthaving a plurality of hook elements and a female component adapted forreleasable engagement with the male component. The female componentcomprises a web having a fibrous structure, wherein the female componentcontains at least a first area and a second area. The first area ismodified such that a peak shear force to disengage the male componentfrom the first area is at least 10% less than a peak shear force todisengage the male component from the second area. Further, at least aportion of the female component is stretchable.

Yet another version of the present invention involves a disposableabsorbent article having an outer cover, a liner superposed over atleast a portion of the outer cover, an absorbent core disposed betweenthe liner and the outer cover and a fastening system. The fasteningsystem having a male component having a plurality of hook elements and afemale component adapted for releasable engagement with the malecomponent. The female component having a fibrous structure and definingat least a first area and a second area, at least a portion of thefemale component is stretchable. The peak shear force to disengage themale component from the first area is at least 10% less than the peakshear force to disengage the male component from the second area.

Also disclosed is a disposable absorbent article having an outer coverhaving a bodyfacing surface and a garment facing surface, a linersuperposed over the bodyfacing surface of the outer cover, theoutercover comprising an outer cover nonwoven web and an absorbent coredisposed between the liner and the bodyfacing surface of the outercover. The disposable absorbent article also has a fastening system. Thefastening system comprises a male component having a plurality of hookelements and a female component adapted for releasable engagement withthe male component. The female component comprises a web having afibrous structure. The outer cover nonwoven web forms the femalecomponent. The female component contains at least a first area and asecond area, where a peak shear force to disengage the male componentfrom the first area is at least 10% less than a peak shear force todisengage the male component from the second area. The male component islocated in a rear region of the disposable absorbent article, and thefirst area is located in a front region of the disposable absorbentarticle.

DRAWINGS

The foregoing and other features, aspects and advantages of the presentinvention will become better understood with regard to the followingdescription, appended claims and accompanying drawings where:

FIG. 1 illustrates a plan view of a disposable absorbent article in anunfolded, flat-out, uncontracted state (i.e., with all elastic inducedgathering and contraction removed), with the bodyfacing surface of thearticle facing the viewer and with portions of the article partially cutaway to illustrate underlying features;

FIG. 2 illustrates a plan view of a disposable absorbent article in anunfolded, flat-out, uncontracted state, with the garment facing surfaceof the article facing the viewer and with portions of the articlepartially cut away to illustrate underlying features with a modifiedarea of a female component;

FIG. 3 illustrates a plan view of a disposable absorbent article in anunfolded, flat-out, uncontracted state, with the garment facing surfaceof the article facing the viewer with a modified area of a femalecomponent;

FIG. 4 illustrates a plan view of a disposable absorbent article in anunfolded, flat-out, uncontracted state, with the garment facing surfaceof the article facing the viewer with a modified area of a femalecomponent; and

FIG. 5 illustrates a representative test sample.

DESCRIPTION

The present invention relates to improved fasteners, and improvedfasteners for use in disposable absorbent articles. As used herein, theterm “disposable” refers to articles which are intended to be discardedafter a limited use and which are not intended to be laundered orotherwise restored for reuse. The disposable absorbent articles of thepresent invention will be described in terms of a disposable diaperwhich is adapted to be worn by infants about the lower torso. It isunderstood that the improved fastening system of the present inventionis equally adaptable for use with other types of disposable absorbentarticles such as adult incontinent garments, children's training pants,surgical gowns and the like.

With regard to the designated surfaces of a disposable absorbent articleand its components, the various upper or bodyfacing surfaces areconfigured to face toward the body of the wearer when the disposableabsorbent article is worn by the wearer for ordinary use. The variousopposing, lower or garment facing surfaces are configured to face awayfrom the wearer's body when the disposable absorbent article is worn bythe wearer.

As used herein, reference to two materials or elements being “joined” isintended to refer to the situation wherein the two materials or elementsare directly joined to one another or where they are indirectly joinedto one another or where they are indirectly joined to an intermediateelement. Similarly, methods of joining two materials or elements includeforming the elements or materials integrally, or attaching the elementstogether such as through the use of adhesive bonds, sonic bonds, thermalbonds, pinning, stitching, or a variety of other attachment techniquesknown in the art, as well as combinations thereof.

“Stretchable”, refers to materials which are either elastic orextensible, that is materials which when elongated in one or moredimensions either exert a force tending to move the material at leastpartially to its original dimensions (elastic), or which remain in theelongated configuration (extensible).

It should be noted that the stretch, elastic or extensible properties ofa stretchable material are determined when the material is dry.Additionally, the percentage of elongation, extension or permanentdeformation can be determined in accordance with the following formula:100*[(L−L _(o))/(L _(o))]where: L=elongated length; and

-   -   L_(o)=initial length.

Referring now to the drawings, FIG. 1 illustrates a disposable absorbentarticle such as a disposable diaper (30) in an unfolded, flat-out,uncontracted state (i.e., with all elastic induced gathering andcontraction removed). Portions of the structure are partially cut awayto more clearly show the interior construction of the diaper (30), withthe surface of the diaper (30) which contacts the wearer facing theviewer. FIGS. 1 and 2 illustrate a disposable diaper (30) as having afront region (32), a rear region (34) and a crotch portion (36) locatedbetween the front and rear regions. The diaper (30) comprises abacksheet (38), a topsheet (40), and an absorbent core (42) situatedbetween the backsheet and the topsheet. The outer edges of the diaper(30) define a periphery (44) with transversely opposed, longitudinallyextending side edges (46); longitudinally opposed, transverselyextending end edges (48); and a system of elastomeric gathering members,such as a system including leg elastics (50) and waist elastics (52).The longitudinal side edges (46) define the leg openings (54) for thediaper (30), and optionally, are curvilinear and contoured. Thetransverse end edges (48) are illustrated as straight, but optionally,may be curvilinear. The diaper (30) may also comprise additionalcomponents to assist in the acquisition, distribution and storage ofbodily waste. For example, the diaper (30) may comprise a transportlayer, such as described in U.S. Pat. No. 4,798,603, issued to Meyer etal., or a surge management layer, such as described in European PatentApplication Publication No. 0 539 703, published May 5, 1993.

The diaper (30) generally defines a longitudinally extending lengthdimension (56), and a laterally extending width dimension (58), asrepresentatively illustrated in FIG. 1. The diaper (30) may have anydesired shape, such as rectangular, I-shaped, a generally hourglassshape, or a T-shape.

The backsheet (38) defines a length and a width which, in theillustrated version, coincide with the length and width of the diaper(30). The absorbent core (42) generally defines a length and width whichare less than the length and width of the backsheet (38), respectively.Thus, marginal portions of the diaper (30), such as marginal sections ofthe backsheet (38), may extend past the transversely opposed,longitudinally extending terminal side edges (60) and/or thelongitudinally opposed, transversely extending terminal end edges (62)of the absorbent core (42) to form side margins (64) and end margins(66) of the diaper (30). The topsheet (40) is generally coextensive withthe backsheet (38), but may optionally cover an area which is larger orsmaller than the area of the backsheet, as desired. The backsheet (38)and topsheet (40) are intended to face the garment and body of thewearer, respectively, while in use. As used herein when describing thetopsheet (40) in relation to the backsheet (38) and vice versa, the term“associated” encompasses configurations in which the topsheet isdirectly joined to the backsheet, and configurations where the topsheetis indirectly joined to the backsheet by affixing portions of thetopsheet to intermediate members which in turn are affixed to at leastportions of the backsheet. The topsheet (40) and the backsheet (38) can,for example, be joined to each other in at least a portion of the diaperperiphery (44) by attachment mechanisms (not shown) such as adhesivebonds, sonic bonds, thermal bonds, pinning, stitching, or a variety ofother attachment techniques known in the art, as well as combinationsthereof.

The topsheet (40) suitably presents a bodyfacing surface which iscompliant, soft feeling, and non-irritating to the wearer's skin.Further, the topsheet (40) may be less hydrophilic than the absorbentcore (42), to present a relatively dry surface to the wearer, and issufficiently porous to be liquid permeable, permitting liquid to readilypenetrate through its thickness. A suitable topsheet (40) may bemanufactured from a wide selection of web materials, such as porousfoams, reticulated foams, apertured plastic films, natural fibers,synthetic fibers (for example, polyester or polypropylene fibers), or acombination of natural and synthetic fibers. The topsheet (40) issuitably employed to help isolate the wearer's skin from liquids held inthe absorbent core (42).

Various woven and nonwoven fabrics may be used for the topsheet (40).For example, the topsheet (40) may be composed of a meltblown orspunbonded web of polyolefin fibers. The topsheet (40) may also be abonded-carded web composed of natural and/or synthetic fibers. Thetopsheet (40) may be composed of a substantially hydrophobic material,and the hydrophobic material may, optionally, be treated with asurfactant, or otherwise processed, to impart a desired level ofwettability and hydrophilicity. Specifically, the topsheet (40) may be anonwoven, spunbond, polypropylene fabric composed of about 2.8 to about3.2 denier fibers formed into a web having a basis weight of about 22gsm and a density of about 0.06 g/cc.

The topsheet (40) may also be surface treated with about 0.3 weightpercent of a surfactant mixture that contains a mixture of AHCOVEL BaseN-62 surfactant and GLUCOPON 220UP surfactant in about a 3:1 ratio basedon a total weight of the surfactant mixture. The AHCOVEL Base N-62surfactant is purchased from Hodgson Textile Chemicals Inc., a businesshaving offices in Mount Holly, N.C., and comprises a blend ofhydrogenated ethoxylated castor oil and sorbitan monooleate in a 55:45weight ratio. The GLUCOPON 220UP surfactant is purchased from HenkelCorporation, Gulph Mills, Pa., and comprises alkyl polyglycoside. Thesurfactant may also include additional ingredients such as aloe. Thesurfactant may be applied by any conventional means, such as spraying,printing, brush coating, foam or the like. The surfactant may be appliedto the entire topsheet (40) or may be selectively applied to particularsections of the topsheet, such as the medial section along thelongitudinal centerline of a diaper, to provide greater wettability ofsuch sections.

The backsheet (38) may suitably be composed of a material which iseither liquid permeable or liquid impermeable. It is generally desirablethat the backsheet (38) be formed from a material which is substantiallyliquid impermeable. For example, a typical backsheet (38) can bemanufactured from a thin plastic film or other flexible liquidimpermeable material. Moreover, the backsheet (38) may be formed from apolyethylene film having a thickness of from about 0.012 mm (0.5 mil) toabout 0.051 mm (2.0 mils). If desirous of presenting the backsheet (38)with a more cloth-like feel, the backsheet may comprise a polyethylenefilm having laminated to the lower or opposing surface thereof anonwoven web, such as a spunbond web of polyolefin fibers. For example,a polyethylene film having a thickness of about 0.015 mm (0.6 mil) mayhave thermally laminated thereto a spunbond web of polyolefin fibers,which fibers have a thickness of about 1.5 to about 2.5 denier perfilament, which nonwoven web has a basis weight of about 24 gsm (0.7osy). Methods of forming such cloth-like outer covers are known to thoseskilled in the art. Further the backsheet (38) may be a stretchablematerial, a method of forming such a material may be found in U.S. Pat.No. 5,226,992 issued to Morman, further various examples of extensiblematerials are described in U.S. Pat. No. 6,264,641 issued to VanGompelet al.; the entire disclosures of which are hereby incorporated byreference in a manner that is consistent herewith

Further, the backsheet (38) may be formed of a woven or nonwoven fibrousweb layer which has been totally or partially constructed or treated toimpart a desired level of liquid impermeability to selected regions thatare adjacent or proximate the absorbent core (42). Still further, thebacksheet (38) may optionally be composed of micro-porous “breathable”material which permits vapors to escape from the absorbent core (42)while still preventing liquid exudates from passing through thebacksheet.

The absorbent core (42) may comprise a matrix of hydrophilic fibers,such as a web of cellulosic fluff, mixed with particles of ahigh-absorbency material commonly known as superabsorbent material. In aparticular version, the absorbent core (42) comprises a mixture ofsuperabsorbent hydrogel-forming particles and wood pulp fluff. The woodpulp fluff may be exchanged with synthetic polymeric, meltblown fibersor with a combination of meltblown fibers and natural fibers. Thesuperabsorbent particles may be substantially homogeneously mixed withthe hydrophilic fibers or may be non-uniformly mixed.

The absorbent core (42) may have any of a number of shapes. For example,the absorbent core (42) may be rectangular, I-shaped or T-shaped. It isoften considered as desirable for the absorbent core (42) to be narrowerin the crotch portion than the rear or front region(s).

The high-absorbency material can be selected from natural, synthetic andmodified natural polymers and materials. The high-absorbency materialscan be inorganic materials, such as silica gels, or organic compounds,such as crosslinked polymers. The term “crosslinked” refers to any meansfor effectively rendering normally water-soluble materials substantiallywater insoluble, but swellable. Such means can comprise, for example,physical entanglement, crystalline domains, covalent bonds, ioniccomplexes and associations, hydrophilic associations, such as hydrogenbonding, and hydrophobic associations or Van der Waals forces.

Examples of synthetic, polymeric, high-absorbency materials include thealkali metal and ammonium salts of poly(acrylic acid) andpoly(methacrylic acid), poly(acrylamides), poly(vinyl ethers), maleicanhydride copolymers with vinyl ethers and alpha-olefins, poly(vinylpyrolidone), poly(vinyl morpholinone), poly(vinyl alcohol), and mixturesand copolymers thereof. Further polymers suitable for use in theabsorbent core include natural and modified natural polymers, such ashydrolyzed acrylonitrile-grafted starch, acrylic acid grafted starch,methyl cellulose, carboxymethyl cellulose, hydroxypropyl cellulose, andthe natural gums, such as alginates, xanthum gum, locust bean gum, andthe like. Mixtures of natural and wholly or partially syntheticabsorbent polymers can also be useful. Processes for preparingsynthetic, absorbent gelling polymers are disclosed in U.S. Pat. No.4,076,663, issued to Masuda et al., and U.S. Pat. No. 4,286,082, issuedto Tsubakimoto et al.

The high-absorbency material may be in a variety of geometric forms. Itis desired that the high-absorbency material be in the form of discreteparticles. However, the high-absorbency material may also be in the formof fibers, flakes, rods, spheres, needles, or the like. Often, thehigh-absorbency material is present in the absorbent core (42) in anamount of from about 5 to about 100 weight percent based on total weightof the absorbent core.

The disposable absorbent articles described herein also comprisefasteners (82) for securing the absorbent article about the waist of thewearer. The illustrated versions of the diaper (30) comprise suchfasteners (82). In at least one version, the fasteners (82) are situatedin the rear region (34) of the diaper (30), and located inboard eachlongitudinal extending side edge (46). The fasteners (82) may beconfigured to encircle the hips of the wearer and engage the backsheet(38) of the front region (32) of the diaper (30) for holding the diaper(30) on the wearer. Suitable fasteners are well known to those of skillin the art and can comprise adhesive tape tab fasteners, hook and loopfasteners, mushroom fasteners, snaps, pin, belts and the like, andcombinations thereof. Desirably, the fasteners (82) are releasablyengageable directly with the garment facing surface of the backsheet(38). Desirably, the fasteners (82) comprise a mechanical fasteningsystem. Alternatively, the diaper (30) may comprise a fastening panel(68) situated in the front region (32) of the garment facing surface ofthe backsheet (38). In such a configuration, the fasteners (82) arereleasably engageable with the fastening panel (68) to maintain thediaper (30) about the waist of the wearer. Such an arrangement providesthe ability to vary the size of the waist opening in very smallincrements over a wide range to fit the waist of the wearer. Thefasteners (82) may have a variety of shapes and sizes which provide thedesired fastening of the diaper (30) about the waist of the wearer.

Desirably, the first fastener component and cooperating fastenercomponent comprise complementary elements of a cooperativelyinterengaging mechanical fastening system. The mechanical fastenercomponents can be provided by mechanical-type fasteners such as hooks,buckles, snaps, buttons and the like, which comprise cooperating andcomplementary, mechanically interlocking components.

As shown in FIGS. 1 and 2, for example, the mechanical fastening systemmay be a hook-and-loop type of fastening system. Such fastening systemstypically comprise engagement members having the form of a “hook” orhook-like, male component, and comprise a cooperating “loop” orloop-like, female component, which engages and releasably interconnectswith the hook component. Desirably, the interconnection is selectivelyreleasable and re-attachable. Conventional systems are, for example,available under the VELCRO trademark.

A configuration which employs a selectively releasable, inter-engagingmechanical fastening system can, for example, locate the first fastenercomponent on the ear (89), and can locate the cooperating, secondfastener component on the fastening panel (68). For example, with therepresentatively shown hook-and-loop fastener, the fastening component,which is attached to the ear (89), may comprise a hook type ofmechanical engagement element, and the complementary fasteningcomponent, is the fastening panel (68) which can comprise a loop type offastening element.

It should also be readily apparent that, in the various configurationsof the invention, the relative positions and/or materials of the firstfastening component and its cooperating, complementary fasteningcomponent can be transposed.

Examples of hook-and-loop fastening systems and components are describedin U.S. Pat. No. 5,019,073 issued to Roessler et al, the entiredisclosure of which is hereby incorporated by reference in a manner thatis consistent herewith. Other examples of hook-and-loop fasteningsystems are described in U.S. Pat. Nos. 5,605,735 and 6,030,373 issuedto VanGompel et al.; the entire disclosures of which are herebyincorporated by reference in a manner that is consistent herewith.Examples of fastening tabs constructed with a carrier layer aredescribed in U.S. Pat. No., 5,624,429 issued to Long et al., the entiredisclosure of which is hereby incorporated by reference in a mannerwhich is consistent herewith.

The loop material can comprise a nonwoven, woven or knit fabric. Forexample, a suitable loop material fabric can be composed of a 2 bar,warp knit fabric of the type available from Guilford Mills, Inc.,Greensboro, N.C. under the trade designation #34285, as well as othertypes of knit fabrics. Suitable loop materials are also available fromthe 3M Company, which has distributed a nylon woven loop under theirSCOTCHMATE brand. The 3M Company has also distributed a linerless loopweb with adhesive on the backside of the web, and 3M knitted loop tape.

The loop material may also comprise a nonwoven fabric having continuousbonded areas defining a plurality of discrete unbonded areas. The fibersor filaments within the discrete unbonded areas of the fabric aredimensionally stabilized by the continuous bonded areas that encircle orsurround each unbonded area, such that no support or backing layer offilm or adhesive is required. The unbonded areas are specificallydesigned to afford spaces between fibers or filaments within theunbonded area that remain sufficiently open or large to receive andengage hook elements of the complementary hook material. In particular,a pattern-unbonded nonwoven fabric or web may comprise a spunbondnonwoven web formed of single component or multi-component melt-spunfilaments. At least one surface of the nonwoven fabric can comprise aplurality of discrete, unbonded areas surrounded or encircled bycontinuous bonded areas. The continuous bonded areas dimensionallystabilize the fibers or filaments forming the nonwoven web by bonding orfusing together the portions of the fibers or filaments that extendoutside of the unbonded areas into the bonded areas, while leaving thefibers or filaments within the unbonded areas substantially free ofbonding or fusing. The degree of bonding or fusing within the bondingareas desirably is sufficient to render the nonwoven web non-fibrouswithin the bonded areas, leaving the fibers or filaments within theunbonded areas to act as “loops” for receiving and engaging hookelements. Examples of unmodified, suitable point-unbonded fabrics aredescribed in U.S. Pat. No. 5,858,515, issued to by Stokes et al., theentire disclosure of which is incorporated herein by reference in amanner that is consistent herewith. As used herein, the term “spunbondweb” refers to a web formed by extruding a molten thermoplastic materialas filaments from a plurality of fine, usually circular, capillarieswith the diameter of the extruded filaments then being rapidly reduced,for example, by fluid-drawing or other well known spunbondingmechanisms. The production of spunbond nonwoven webs is illustrated inU.S. Pat. No. 4,340,563, issued to Appel, et al., the entire disclosureof which is incorporated herein by reference in a manner that isconsistent herewith.

The loop material need not be limited to a discrete or isolated patch onthe outward surface of the article. Instead, the loop material can beprovided by a substantially continuous, outer fibrous layer which isassembled, integrated or otherwise joined to extend over a predeterminedsurface area of the desired article. For example, the outer fibrouslayer may be arranged to extend over substantially the total exposedsurface area of a cloth-like outer cover employed with the article.Further, the outer cover can comprise an outer nonwoven layer thatfunctions as a cooperating fastener component.

The engagement force between the selected first fastener component andits appointed and cooperating second fastener component should be largeenough and durable enough to provide an adequate securement of thearticle on the wearer during use. In particular arrangements, especiallywhere there are sufficiently high levels of engagement shear forceprovided by the fastening system, the fastening engagement may provide apeel force value of not less than a minimum of about 40 grams-force(gmf) per inch of the “width” of engagement between the first and secondfastener components. In further arrangements, the fastening engagementmay provide a peel force value of not less than about 100 gmf/inch toprovide improved advantages. In desired configurations, the fasteningengagement may provide a peel force value of not less than about 200 gmfper inch of the “width” of engagement between the first and secondfastener components. Alternatively, the peel force is not less thanabout 300 gmf/inch, and optionally is not less than about 400 gmf/inchto further provide improved benefits. In other aspects, the peel forceis not more than about 1,200 gmf/inch. Alternatively, the peel force isnot more than about 800 gmf/inch, and optionally is not more than about600 gmf/inch to provide improved performance.

The engagement force between the selected first fastener component andits appointed and cooperating second fastener component may additionallyprovide a shear force value of not less than about 400 gmf per squareinch of the area of engagement between the first and second fastenercomponents. Alternatively, the shear force is not less than about 1,000gmf/in², and optionally, is not less than about 1,700 gmf/in². Infurther aspects, the shear force can be up to about 4,400 gmf/in², ormore. Alternatively, the shear force is not more than about 3,900gmf/in², and optionally is not more than about 3,500 gmf/in² to provideimproved performance.

The engagement force between a given male component and a given femalecomponent may be changed by selective modification of the femalecomponent. Further, by selectively modifying a portion of the femalecomponent, a first area and a second area may be formed, the first areabeing modified, and the second are being unmodified. A reduction ofengagement force may be achieved by printing with wax-based inks. As theexamples described hereinafter show, printing with wax based inksreduces the shear force required to separate the male and femalecomponents. While not to be bound by any theory, but it is believed thatthe reduction of engagement is caused by the wax based inks interferingwith the ability of the male component to engage the female component.An advantage of this selective modification of the female component isthat a given base material with a given engagement force may be modifiedto reduce the engagement force by a lesser or greater degree. This maybe highly advantageous where the female component has been designed tobe very soft and cloth-like and thereby susceptible to abrasion by themale component. By reducing the engagement force, the female componentmay remain soft and cloth-like while improving its abrasion resistance.This reduction of engagement may be accomplished in at least two ways.First, the reduction of engagement may be increased or decreased bymodifying the amount of add-on of ink (the amount of ink applied perunit area). Within ranges, an increase of ink add-on will increase thereduction of engagement, and a decrease of ink add-on will decrease thereduction of engagement. In addition to ink, that female component maybe coated with a number of materials, for example high melt flowpolymers, mPE, MPP, hot melt adhesives, APAO, elastomeric olefinics,non-tacky polymers or other suitable polymeric matrial, or combinationsof the aforementioned. In addition to printing, any one or combinationsof the above may be applied to the female component by misting,spraying, streaking, or slot coating.

A second way to adjust the level of reduction of engagement is to modifythe area that is treated, on a micro scale. For example, instead ofprinting the material with a uniform layer of ink, the material can beprinted with small dots or lines, such that, there are printed areas,and un-printed areas. Material may be printed such that there is more orless coverage in a given area. In this way, the amount of reduction ofengagement can be “adjusted”, by increasing the area printed,approaching complete coverage to achieve the reduction of engagement ofcomplete coverage, or decreasing the area printed, approaching nocoverage to achieve no reduction.

A second method used to modify the engagement of a given femalecomponent is embossing. While not to be bound by any theory, but it isbelieved that the reduction of engagement is caused by the embossinginterfering with the ability of the male component to engaging thefemale component. Embossing takes place when a material comes in contactwith a surface and energy is transferred from the surface to thematerial which in some way permanently modifies the material. Thissurface may be a roller, a flat anvil or alternatively, it may be tworollers that form a nip. The energy may be in the form of pressure,thermal, ultrasonic or other suitable form, or combinations of theseforms. As with the method of printing, the reduction of engagement maybe increased or decreased in at least two ways. First, the reduction ofengagement may be increased or decreased by modifying the level ofembossing. Within ranges, the level of embossing may be increased byincreasing the amount of energy that is transferred from the surface tothe material. For instance, with thermal embossing, one way to increasethe level of embossing may be to increase the temperature of theembossing surface. Correspondingly, reducing the temperature of theembossing surface may result in a decrease in the level of embossing. Anincrease in the level of embossing may increase the reduction ofengagement, and a decrease in the level of embossing may decrease thereduction of engagement.

A second way the reduction of engagement may be increased or decreasedis by use of a micro-scale embossing pattern. As with printing, anembossing pattern may have a smaller bond area, which may correspondwith a lower reduction of engagement; alternatively, an embossingpattern may have a larger bond area, which may correspond with a higherreduction of engagement. Embossing patterns with different bond areasare well known in the art.

The reduction of engagement is determined by measuring the engagementforce of the un-modified area (F₀), and the engagement force of themodified area (F₁). The equation for the percent reduction of engagementis 100*[(F₀−F₁)/(F₀)].

The difference between the engagement between the modified (first area)and unmodified area (second area) may be increased or decreased by themethods described above. Desirably, the reduction of engagement is noless then 5%; alternatively, no less than 10%; alternatively, no lessthan 15%; alternatively, no less than 22%; alternatively, no less than30%; alternatively, no less than 37%; alternatively, no less than 45%;alternatively, no less than 49%; alternatively, no less than 54%;alternatively, no less than 60% and finally, alternatively, no less than70%. Desirably, the reduction of engagement is no more than 65%;alternatively, no more than 58%; alternatively, no more than 52%;alternatively, no more than 45%; alternatively, no more than 39%;alternatively, no more than 33%; alternatively, no more than 29%;alternatively, no more than 24%; alternatively, no more than 21%;alternatively, no more than 18%; alternatively, no more than 14%;alternatively, no more than 11%; and finally, alternatively, no morethan 5%. Thus, the reduction of engagement is no less than 5% and nomore than 70%; although the approximate percent may vary according to,inter alia, the general design and intended use of the female fastener.

Desirably, the percentage of the area of the female component that ismodified to reduce engagement is no less then 1; alternatively, no lessthan 6; alternatively, no less than 13; alternatively, no less than 15;alternatively, no less than 19; alternatively, no less than 25;alternatively, no less than 27; alternatively, no less than 33;alternatively, no less than 36; alternatively, no less than 41;alternatively, no less than 45; alternatively, no less than 47;alternatively, no less than 52; alternatively, no less than 55;alternatively, no less than 61; alternatively, no less than 63;alternatively, no less than 68; alternatively, no less than 71;alternatively, no less than 77; alternatively, no less than 81;alternatively, no less than 83; alternatively, no less than 87;alternatively, no less than 92; alternatively, no less than 97; andfinally, alternatively, no less than 98. Desirably, the percentage ofthe area of the female component that is modified to reduce engagementis no more than 99; alternatively, no more than 96; alternatively, nomore than 91; alternatively, no more than 88; alternatively, no morethan 82; alternatively, no more than 81; alternatively, no more than 76;alternatively, no more than 72; alternatively, no more than 68;alternatively, no more than 63; alternatively, no more than 60;alternatively, no more than 55; alternatively, no more than 51;alternatively, no more than 48; alternatively, no more than 45;alternatively, no more than 40; alternatively, no more than 37;alternatively, no more than 33; alternatively, no more than 27;alternatively, no more than 25; alternatively, no more than 19;alternatively, no more than 14; alternatively, no more than 12;alternatively, no more than 7; and finally, alternatively, no more than5. Thus, the percentage of the area of the female component that ismodified to reduce engagement typically is no less than 1 percent and nomore than 99 percent; although the approximate percent may varyaccording to, inter alia, the general design and intended use of thefemale fastener.

The female component may be a point-unbonded fabric as described in U.S.Pat. No. 5,858,515, issued to by Stokes et al, and further as found as afastening panel (68) on commercially available HUGGIES ULTRATRIMdiapers. Alternatively, the female component may be a stretchablematerial, a method of forming such a material may be found in U.S. Pat.No. 5,226,992 issued to Morman, further various examples of suitablematerials are described in U.S. Pat. No. 6,264,641 issued to VanGompelet al.

In desired configurations, the female component can provide a stretchelongation as measured at 250 g/in. Desirably the female component canprovide a stretch elongation that is no less than 3%, alternatively, noless than 5% of the backsheet area; alternatively, no less than 10% ofthe backsheet area; alternatively, no less than 15% of the backsheetarea; and finally, alternatively, no less than 20%. Desirably the femalecomponent can provide a stretch elongation measure at 250 g/in that isno more than 30%; alternatively, no more than 25%; alternatively, nomore than 20%; alternatively, no more than 15%; and finally,alternatively, no more than 10%. Thus, the female component typicallycan provide a stretch elongation measured at 250 g/in that is no lessthan 3% and no more than 30%; although the approximate percent may varyaccording to, inter alia, the general design and intended use of thefemale component.

The female component may form the backsheet. Alternatively, the femalecomponent may be attached to the backsheet (38). Desirably, the area ofthe female component is no less than 1% of the back sheet area;alternatively, no less than 9% of the backsheet area; alternatively, noless than 18% of the backsheet area; alternatively, no less than 27% ofthe backsheet area; alternatively, no less than 36% of the backsheetarea; alternatively, no less than 45% of the backsheet area;alternatively, no less than 52% of the backsheet area; alternatively, noless than 61% of the backsheet area; alternatively, no less than 68% ofthe backsheet area; alternatively, no less than 77% of the backsheetarea; alternatively, no less than 83% of the backsheet area;alternatively, no less than 92% of the backsheet area; and finally,alternatively, no less than 98% of the backsheet area. Desirably, thearea of the female component is no more than 100% of the backsheet area;alternatively, no more than 91% of the backsheet area; alternatively, nomore than 82% of the backsheet area; alternatively, no more than 76% ofthe backsheet area; alternatively, no more than 68% of the backsheetarea; alternatively, no more than 60% of the backsheet area;alternatively, no more than 51% of the backsheet area; alternatively, nomore than 45% of the backsheet area; alternatively, no more than 37% ofthe backsheet area; alternatively, no more than 27% of the backsheetarea; alternatively, no more than 19% of the backsheet area;alternatively, no more than 12% of the backsheet area; and finally,alternatively, no more than 5% of the backsheet area. Thus, the area ofthe female component typically is no less than 1% and no more than 100%of the backsheet area; although the approximate percent may varyaccording to, inter alia, the general design and intended use of thefemale component.

As shown in FIGS. 3 and 4, the modified area (70) of the femalecomponent may be shaped and positioned in many ways. FIG. 3 illustratesa diaper having an outer cover comprising a nonwoven web. The nonwovenweb functions as a female fastening component, with a first region andsecond region. The first region defined by coverage of printing orembossing denoted by a plurality of star-shaped elements. FIG. 4illustrates a diaper having an outer cover comprising a nonwoven web.The nonwoven web functions as a female fastening component, with a firstregion and second region. The first region defined by coverage ofprinting or embossing denoted by a plurality of circular shapedelements. With regard to the location of the first region, on a diaper(30) with fasteners (82) located in the rear region (34), the area (70)of the female component that is modified may be located in the frontregion (32). Further, the area (70) of the female component that ismodified may consist of a simple geometric shape such as a rectangleshown in FIG. 4. Alternatively, the area of the female component that ismodified may consist of a more complex shape, such as a pattern of twooverlapping diamonds shown in FIG. 3. The shape and size may varyaccording to the general design and intended use of the femalecomponent.

The shear strength of a mechanical fastening system can be determined inaccordance with the following method.

Test Method: Shear Strength

Test Procedure

This procedure is a tensile bench test to measure the shear forcerequired to separate a mechanical fastening system that joins twomaterials. The shear force of separation is measured by determining loadvalues as the two materials are pulled apart parallel to their plane ofcontact. The shear strength test values are an indication of how wellthe mechanical fastening system stays engaged against in-plane shearforce. The sample is pulled in the tensile tester until the sample pullsapart. Shear strength is the peak load result. Shear strength may benormalized by dividing by the contact area resulting in a force perarea.

1. Overview

A material sample of two material layers joined by a mechanicalfastening system such as a hook and loop system is assembled. Thefastening system joins two pieces of material that overlap in thelanding area. The sample is prepared by aligning and applying the hookmaterial to the loop material, and by rolling a 4.5 lb. (2.04 kg)mechanical roller over the fastening system to engage the fastener. Thesample is then placed between clamps on a tensile tester. One piece ofmaterial is held in the upper clamp, while the other is held in thelower clamp. The fastening system is arrayed between the clamps,approximately parallel to the edges of the clamp faces. The width of thehook material is 13 mm, the width of the loop material is approximately64 mm, and the hook overlaps the loop 50 mm. The gage length is 3 inches(76 mm) between the edges of the clamp faces. The term “load” refers tothe gram value measured by the load cells in the tensile tester.

The jaws are separated at a controlled rate of 12 inch/min (305 mm/minuntil) the fastening system is pulled apart. The load values generatedon the material throughout this process are recorded. The load as afunction of elongation is recorded on a computer.

Load values for samples of non-standard widths and lengths should benormalized by multiplying or dividing by the factor by which the sampleoverlap area deviates from 13 mm by 50 mm. For example, the peak loadvalue derived by pulling apart a 1 inch (25.4 mm) wide by 50 mm longsample should be multiplied by 13/25.4.

Suitable materials comprise hook and loop fastening systems, which maycomprise or be attached to materials used to form the disposablegarments described herein.

2. Apparatus and Materials

2.1 Constant Rate of Extension (CRE) tensile tester such as an MTStensile tester model Sintech 1/G; available from MTS SystemsCorporation, located at 1400 Technology Drive, Eden Prairie, Minn., USA.

2.2 Load cells: A suitable cell selected so the majority of the peakload values fall between 10% and 90% of the manufacturer's recommendedranges of load cell's full scale value; for example, Model 100Navailable from MTS Systems Corporation, located at 1400 TechnologyDrive, Eden Prairie, Minn., USA.

2.3 Operating software and data acquisition system such as MTSTestWorks® for Windows software version 3.10; available from MTS SystemsCorporation, located at 1400 Technology Drive, Eden Prairie, Minn., USA.

2.4 Grips: pneumatic-action grips, top and bottom, identified as partnumber 38.00716 available from MTS Systems Corporation.

2.5 Grip faces: 25 by 75-mm (1 by 3-inch) interlocking faces such as areavailable from MTS Systems Corporation.

2.6 Roller: 4.5 lb (2.04 kg)mechanical roller available fromChemsultants International, Mentor, Ohio, USA.

3. Conditioning

Reasonable ambient conditions are required for testing. The instrumentsused should be calibrated as described in the manufacturer'sinstructions for each instrument.

4. Test Specimen (Illustrated in FIG. 5)

The loop material sample (101) is cut to have a width (a) ofapproximately 2.5 in. (64 mm) and a length (b) of approximately 4 in(102 mm). A hook material sample (102) having a width (f) of 13 mm and alength (g) of approximately 4 in. (102 mm) is placed onto the loop sideof the loop material sample (101) such that the hook material sample(102) overlaps (c) the loop material sample (101) 50 mm, perpendicularfrom the 64 mm wide edge, centered on the 64 mm. The joined materialsshould not be handled or pressed.

The specimen is placed in a hard flat surface, and the test sample isthen pressed down with a standard 4.5 lb (2.04 kg) mechanical roller byrolling the roller across the hook/loop engagement area back and forthin the length direction. The centerline of the sample should be alignedwith the centerline of the face of the roller.

The specimen is tested using the tensile test procedure that follows. Atleast four specimens of each sample should be tested, and the resultsaveraged.

5. Procedure

Tensile Tester Test Conditions:

Preload No Test speed 305 mm/min Gage length (h): 3 inches (76 mm)Number of cycles: 1

A. Using the tensile frame pushbutton controls for crosshead position,move grips to provide a gage length (h) of 3 inches (76 mm). Tare thecrosshead channel to this initial gage length.

B. Without touching the fastening area, hold a material specimen so thatthe loop material is up and the hook material is down. Place the loopmaterial in the upper jaw (103) of the tester, such that loop materialextends (e) below the lower edge of the upper jaw (103) 64 mm. Place theloop material in the upper jaw (103) such that it is centered in thehorizontal direction, with the hook material extending below the centerof the upper jaw (103).

C. Close the upper jaw (103) on the specimen and tare the load channel.

D. Hold the specimen in such a way as to minimize slack in the specimen,but do not place the specimen under tension, and close the lower jaw(104) on the hook material.

E. Run the test using the above parameters by clicking on the RUNbutton.

F. When the test is complete, save the data to a sample file.

G. Remove the specimen from the jaws (103, 104).

H. Run additional specimens of a given sample using steps B-G; the datafor all specimens should be saved to a single file.

I. Continue testing all samples in this manner.

J. Data are reported as the peak load and the total energy under theload-extension curve.

The following examples were tested using the method described above,with noted deviations.

EXAMPLES

All Examples used Velcro HTH 851 male component with a 13 mm width.

Example One (Comparative Example)

Two layer 1.5 total osy Point UnBonded spunbond. The top layer comprises49% PP, 48.5% copoly, 1% OB and 1.5% TiO₂ with 27.1 micron fibers. Thebottom layer comprises 97.5% PP, 1.5% OB and 1.0% TiO₂ with 24.9 micronfibers. The top layer comprises 60% of the web. TABLE 1 Example 1 SamplePeak Load (g) Total Energy (g-cm) 1 3,717 7,791 2 4,185  10,294 3 4,284 10,456 4 3,513 6,857 5 4,085 8,164 6 4,179  10,652 7 4,319  10,961Average 4,040 9,309

Example 2 (Comparative Example)

The material from Example 1 was printed using a MacDermid ColorSpanDispalyMaker Express Printer, 4 color CMYK.

-   -   Ink used: Hot-melt phase change wax inks (aka Wax-Jet inks)        -   DisplayMaker Express Ink Pucks    -   Ink drop size: 80 pico liters

Printer and inks available from MacDermid ColorSpan Corp., 6900 ShadyOak Road, Eden Prairie, Minn. 55444.

Results are shown in Table 2. TABLE 2 Example 2 Sample Peak Load (g)Total Energy (g-cm) 1 1,972 3,793 2 2,762 5,748 3 2,159 3,945 4 3,3725,890 5 3,224 5,899 6 1,982 3,779 7 2,219 4,003 8 2,828 5,208 Average2,565 4,783

Example 3 (Comparative Example)

Three layer Neck bonded laminate. Top and bottom layer comprising 56%necked 0.85 osy Polypropylene Spunbond. The middle comprising 40 gsmKraton G2755 film.

The material tested for examples 3 and 4 were 43 mm in width instead ofthe 64 mm of width for examples 1 and 2. This corresponds with dimension(a) from the test procedure. Further, the material sample was cut suchthat the stretch direction corresponded with the “b” dimension.

Results are shown in Table 3. TABLE 3 Example 3 (comparative example)Sample Peak Load (g) Total Energy (g-cm) 1 1,042 4,387 2 1,291 4,335 31,392 5,987 4 1,404 6,242 5 1,186 4,646 Average 1,263 5,119

Example 4 (Comparative Example)

The material from Example 3 was ultrasonically bonded with a Branson 920Plunge Bonder using a 13 mm horn and a flat anvil. The hold time was3.00 seconds, the weld time was 3.00 seconds, the pressure was 500 kPa,and the trigger was 20. The area engaged by the hook material includedonly the portion of the material that was ultrasonically bonded.

Results are shown in Table 4. TABLE 4 Example 4 Sample Peak Load (g)Total Energy (g-cm) 1 957 1,046 2 909 1,187 3 966 1,215 4  1,113 1,536Average 986 1,246

A comparison of tables 1 and 2 indicates a reduction of engagement forceof average peak load of 36.5 percent. Further, a comparison of tables 3and 4 indicates a reduction of engagement force of 21.9 percent.

Having described the invention in rather full detail, it will be readilyapparent that various changes and modifications can be made withoutdeparting from the spirit of the invention. All of such changes andmodifications are contemplated as being within the scope of theinvention as defined by the subjoined claims.

1. A fastening system suitable for incorporation into a disposableabsorbent article, the fastening system comprising: a male componenthaving a plurality of hook elements; and a female component adapted forreleasable engagement with the male component, the female componentcomprising a web having a fibrous structure, wherein the femalecomponent contains at least a first area and a second area, the firstarea is modified such that a peak shear force to disengage the malecomponent from the first area is at least 10% less than a peak shearforce to disengage the male component from the second area, and at leasta portion of the female component is stretchable.
 2. The fasteningsystem of claim 1, wherein the peak shear force to disengage the malecomponent from the first area is at least 20% less than the peak shearforce to disengage the male component from the second area.
 3. Thefastening system of claim 1, wherein at least a portion of the femalecomponent is stretchable at least 10% when loaded at 250 g/in.
 4. Thefastening system of claim 1, wherein at least a portion of the femalecomponent is stretchable at least 15% when loaded at 250 g/in.
 5. Thefastening system of claim 1, wherein the female component is elastic. 6.The fastening system of claim 1, wherein the first area is at least 10%of the female component's area.
 7. The fastening system of claim 1,wherein the first area is at least 20% of the female component's area.8. The fastening system of claim 1, wherein the first area is less than80% of the female component's area.
 9. The fastening system of claim 1,wherein the first area is modified with one of ultrasonic embossing,pressure embossing or thermal embossing.
 10. The fastening system ofclaim 1, wherein the first area is modified with ink or polymericmaterial.
 11. An absorbent article having a fastening system, thefastening system comprising a male component having a plurality of hookelements and a female component adapted for releasable engagement withthe male component, the female component comprising a web having afibrous structure, wherein the female component contains at least afirst area and a second area, the first area is modified such that apeak shear force to disengage the male component from the first area isat least 10% less than a peak shear force to disengage the malecomponent from the second area, and at least a portion of the femalecomponent is stretchable.
 12. The absorbent article of claim 11, whereinthe peak shear force to disengage the male component from the first areais at least 20% less than the peak shear force to disengage the malecomponent from the second area.
 13. The absorbent article of claim 11,wherein at least a portion of the female component is stretchable atleast 10% when loaded at 250 g/in.
 14. The absorbent article of claim11, wherein the female component is elastic.
 15. The absorbent articleof claim 11, wherein the first area is at least 10% of the femalecomponent's area.
 16. The absorbent article of claim 11, wherein thefirst area is at least 20% of the female component's area.
 17. Theabsorbent article of claim 11, wherein the first area is less than 80%of the female component's area.
 18. The absorbent article of claim 11,wherein the first area is modified with one of ultrasonic embossing,pressure embossing or thermal embossing.
 19. The absorbent article ofclaim 11, wherein the first area is modified with ink or polymericmaterial.
 20. A disposable absorbent article comprising: an outer cover;a liner superposed over at least a portion of the outer cover; anabsorbent core disposed between the liner and the outer cover; and afastening system, the fastening system comprising a male componenthaving a plurality of hook elements and a female component adapted forreleasable engagement with the male component, the female componenthaving a fibrous structure and defining at least a first area and asecond area, at least a portion of the female component is stretchable;wherein a peak shear force to disengage the male component from thefirst area is at least 10% less than a peak shear force to disengage themale component from the second area.
 21. The disposable absorbentarticle of claim 20, wherein the female component has an area, the backsheet has an area, and the female component area is less than 50% of thebacksheet area.
 22. The disposable absorbent article of claim 20,wherein the female component has an area, the back sheet has an area,and the female component area is at least 50% of the backsheet area. 23.The disposable absorbent article of claim 20, wherein the peak shearforce to disengage the male component from the first area is at least20% less than the peak shear force to disengage the male component fromthe second area.
 24. The disposable absorbent article of claim 20,wherein at least a portion of the female component is stretchable atleast 10% when loaded at 250 g/in.
 25. The disposable absorbent articleof claim 20, wherein the female component is elastic.
 26. The disposableabsorbent article of claim 20, wherein the first area is at least 10% ofthe female component's area.
 27. The disposable absorbent article ofclaim 20, wherein the first area is at least 20% of the femalecomponent's area.
 28. The disposable absorbent article of claim 20,wherein the first area is less than 80% of the female component's area.29. The disposable absorbent article of claim 20, wherein the first areais modified with one of ultrasonic embossing, pressure embossing orthermal embossing.
 30. The disposable absorbent article of claim 20,wherein the first area is modified with ink or polymeric material.
 31. Adisposable absorbent article comprising: an outer cover having abodyfacing surface and a garment facing surface; a liner superposed overthe bodyfacing surface of the outer cover, the outercover comprising anouter cover nonwoven web; an absorbent core disposed between the linerand the bodyfacing surface of the outer cover; and a fastening system,the fastening system comprising a male component having a plurality ofhook elements and a female component adapted for releasable engagementwith the male component, the female component comprising a web having afibrous structure, wherein the outer cover nonwoven web forms the femalecomponent, the female component contains at least a first area and asecond area, a peak shear force to disengage the male component from thefirst area is at least 10% less than a peak shear force to disengage themale component from the second area, the male component is located in arear region of the disposable absorbent article, and the first area islocated in a front region of the disposable absorbent article.
 32. Thedisposable absorbent article of claim 31, wherein the peak shear forceto disengage the male component from the first area-is at least 20% lessthan the force to disengage the male component from the second area. 33.The disposable absorbent article of claim 31, wherein at least a portionof the female component is stretchable at least 10% when loaded at 250g/in.
 34. The disposable absorbent article of claim 33, wherein thefemale component is elastic.
 35. The disposable absorbent article ofclaim 31, wherein the first area is at least 10% of the femalecomponent's area.
 36. The disposable absorbent article of claim 35,wherein the first area is at least 20% of the female component's area.37. The disposable absorbent article of claim 31, wherein the first areais less than 80% of the female component's area.
 38. The disposableabsorbent article of claim 31, wherein the first area is modified withone of ultrasonic embossing, pressure embossing or thermal embossing.39. The disposable absorbent article of claim 31, wherein the first areais modified with ink or polymeric material.